[jdbc-v2] Option to trim trailing NULs from FixedString on read #3288

getString() / getObject() on a FixedString(N) column return all N bytes, trailing \0 included (BinaryStreamReader decodes new String(bytes, 0, precision)).

That matches ClickHouse semantics. But Tableau 2026.3.0 no longer hides the NULs (2026.2.1 did), so Tableau users see "Dario Medina\0\0\0…". The Tableau connector can't trim on its side, and output_format_trim_fixed_string only applies to text formats, not RowBinary.

Repro (clickhouse-jdbc 0.11.0, ClickHouse 26.10.3.7):

ResultSet rs = conn.createStatement().executeQuery("SELECT toFixedString('Dario', 10)");
rs.next();
rs.getString(1);  // "Dario\0\0\0\0\0", length 10

Ask: an opt-in connection property (e.g. jdbc_trim_fixed_string=true) that strips trailing \0 from FixedString on read. Off by default; the Tableau connector would enable it.

Related: #2929